Moving Docker's storage directory to different location
Edit file /lib/systemd/system/docker.service
and replace line:
ExecStart=/usr/bin/dockerd -H fd:// $DOCKER_OPTS
with following line:
ExecStart=/usr/bin/dockerd -g /new/path/docker -H fd:// $DOCKER_OPTS
where /new/path/docker specifies destination directory that shold store Docker's images.
Stop Docker service:
sudo systemctl stop docker
Make sure that Docker service stopped properly:
sudo ps aux | grep -i docker | grep -v grep
If the command above does not output anything that it is all OK.
Because Docker systemd unit configuration file has changed you have to reload systemd configuration.
You can do it with following command:
Move all content of /var/lib/docker directory to the new desired location:
sudo rsync -aqxP /var/lib/docker/ /new/path/docker
If you want to have access to the new Docker's storage area then you should change its owner nad group:
sudo chmod -R username:groupname /new/path/docker
Start Docker service:
sudo systemctl start docker
Make sure that the service runs properly:
ps aux | grep -i docker | grep -v grep
If the command above will give some output then everything is OK.